interesting observation, small product shots

i made an interesting and unexpected observation tonight. some time ago, i used a silver reflecting garage-type light with a 150 watt incandecent bulb shot through a home made diffuser of white silk cloth to shoot a die-cast model car. that shot was with a zoom lens at 65mm and required f/22 to get the desired depth of field. the exposure time was 1/4 sec at iso100.

tonight i used a 420ex bounced into a 60" umbrella. the distance from model car to center of the umbrella was about 4-5 feet. i used a 50mm lens. i took a shot at f/16 and guess what? the shot was very under exposed. this was no doubt due to lack of output from the flash. i shot again at f/11 and f/9.5 and the shot was exposed properly.

in both cases the lens was about 3-4ft from the model.

the observation was this: to get the required depth of field to get the whole car front-to-back in sharp focus, i ran out of flash vs. using a continuous light source and longer exposure.

in this specific situation, where you are using a medium to long lens fairly close to your subject and thus need a higher f/stop for depth of field, one would probably need a pretty darn powerful flash. perhaps an AB800? although, f/11 to f/16 is really only 1 stop. but looking at the pictures again, f/11 was about 1/2stop underexposed and i still would have wanted f/22 to get the back of the car more in focus so that'd translate to needing 2 stops more light output from the flash, or moving it that much closer. ...

whatever, the point is, i didn't think of the fact that you can't just shoot a longer exposure with a flash vs. a continuous lightsource... however underpowered the continuous lightsource may be.

You could use a more effieciant light modifier. I have a homemade 1.5'x1.5' softbox that i made for shooting macro and other small stuff and at 2 feet away i can get above f22(a 1/3 or 2/3 higher than f22 i cant remember exactly) at full power on my sigma 500 super. This isnt as soft as your umbrella would be though.

If you really need too you could turn the lights off and fire than flash twice or more.

Umbrellas are pretty inefficient when used with hotshoe flash units.
Try firing the flash unit through the same home-made silk diffuser you used with the tungsten light. You could put it pretty close, possibly only inches away (not sure how big your diffusion panel is).

You reached an important epiphany though. Flash lighting is most useful when either the camera or the subject is moving and slow shutter speeds are not practical.

Even with 2000ws lights, you run out of power for small apertures. A common studio technique for still objects (products) is to open the shutter in the dark, then fire the flash with the Open Flash button multiple times. If you need 1EV light, fire 2x, if you need 2EV light, fire 4x. 3EV light, fire 8x. 4EV light, fire 16x. Of course, for small aperture shooting you need beefy lights to begin with, but it is not uncommon to have to resort to this method even with behemoth flash power!

Wilt wrote in post #2302147
Even with 2000ws lights, you run out of power for small apertures. A common studio technique for still objects (products) is to open the shutter in the dark, then fire the flash with the Open Flash button multiple times. If you need 1EV light, fire 2x, if you need 2EV light, fire 4x. 3EV light, fire 8x. 4EV light, fire 16x. Of course, for small aperture shooting you need beefy lights to begin with, but it is not uncommon to have to resort to this method even with behemoth flash power!

I once gave a demonstration on pinhole photograph after dark. I was using several identical pinhole cameras made from cast off Polaroid "Swinger" type cameras loaded with an enlarging paper negative (about ISO 2, F/250 or so).

Test exposures determined I needed to fire a flash head connected to a 500 W-s pack about 30 times to get proper exposure.

Several of the demonstration participants used the cameras and the power pack to make exposures right there, and we had a small contest after we processed the paper negatives and produced wet contact prints from them.

In that case we did not even have to turn off or dim the room lights as that level of illumination was insignificant to the overall exposure.

If one full power flash is not enough, keep flashing.

Enjoy! Lon

i'll try the flash fired through that diffuser. come to think of it, with the diffuser and continuous light, i had the diffuser about 4" or so above the model. so this brings up a fairly obvious point of having too big a light modifier for your subject!

it never occurred to me that a studio would use multiple fires of a flash in high f/stop shooting. good to know these things.

these definitely will be things to keep in mind if/when i switch to studio strobes.

SgWRX wrote in post #2301393
.......the observation was this: to get the required depth of field to get the whole car front-to-back in sharp focus, i ran out of flash vs. using a continuous light source and longer exposure.......

I agree with you 100%.

I have been using a screw in bulb flash, a 420ex and two old speedlite A's all flat out and still seem to need more.

The fist shot of the 1/18th scale girly was in a light tent using all off the above flashes.

The second shot was outside of the tent with three flashes (IIRC) and bouncing the 430ex.

I'm glad someone else has come to this conclusion. I thought I was going mad.

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ha! nope, you're not going mad. i wonder if there are any big quality of light differences between a continuous light/long exposure and powerful strobe/short exposure.

i think the only concern would be if there would be more sensor noise for a longer exposure, but 1/4 sec or even 1-4 seconds doesn't seem like it would be that bad.